Process of removing and recovering metal coatings from metallic bases



(No Model.) 7

- T. G. HUNTER. PROCESS OF REMOVING AND REGOVERING METAL UOATINGS FROM METALLIG BASES.

No. 529,863. Patented Nov. 27, 1894.

I hi {"IEHIH HIIIIIH' UNITED STATES PATENT OFFICE.

THOMAS G. HUNTER, OF PHILADELPHIA, PENNSYLVANIA.

PROCESS OF REMOVING AND RECOVERING METAL COATINGS FROM METALLIC BASES.

SPECIFICATION forming part of Letters Patent N 0. 529,863, dated November 27, 1894.

Application filed January 30,1894. Serial No. 498,454, (No specimens.)

To all whom it may concern:

Be it known that I, THOMAS G. HUNTER, a citizen of the United States, and a resident of the city of Philadelphia, in the State of Pennsylvania, have invented a certain new and useful Process of Removing and Recovering Metal Coatings from Metallic Bases; and-I do hereby declare the following to be a full, clear, and exact description thereof, reference being had to the accompanying drawing, forming part of this specification.

My invention has relation to the treatment of metals consisting of a base of sheet metal and a coating of alloy, or other metal, for the.

purpose of separating the two metals and reclaiming them in their separate conditions.

In Letters Patent of the United States, No. 511,846, issued to me January 2, 1894, I have described and claimed a process for removing tin from scrap, referring in the process to the employment of sulphateof copper as the active agent. My present application pertains to the same class of invention, and has for its object the reclaiming and separating of combined metals consisting of a base of one metal and a coating of another metal, or alloy, for com mercial purposes, and which can be operated upon large quantities of metal at a comparatively small cost.

In the composition of soluble neutral com pounds the metal contained or carried therein operates to exclude or occupy the place of hydrogen, as for example should sulphuric acid H 80, be employed, the presence of the hydrogen, would prevent the operation of the acid radical upon the metal coating of the material to be operated upon in the process hereinafter described, because of the greater affinity of the sulphuric acid radical for the hydrogen than for the metal coating. It is therefore necessary that the soluble neutral compound (containing the acid radical), to be employed as the active agent in my process, shall contain a metal or material which practically excludes the hydrogen, and which, at the same time, shall have less affinity for the acid radical than the coating metal of the combined metal scrap to be operated upon.

I have also simultaneously filed application for Letters Patent of the United States for an improvement in the process of removing and recovering metalcoatings from metallic bases, Serial Nos. 498,453 and 498,445, in which the active agents employed belong to a difierent general class from those specially noted in the present application.

In carrying out my present invention I employ any of the neutral salts of copper included in the nitroxyl group. Of these I preferably employ nitrateof copper.

Where the coated metal to be operated upon is what is known as tin scrap, and the metal to be removed is tin and the base iron, when nitrate of copper is used the tin having a greater affinity for the acid radical of the nitrate of copper, the copper will be at once precipitated and the acid will attack the tin until the .tin is all removed and held'in solution as nitrate of tin, which-tin in turn will be precipitated by the iron forming, with the acid radical, nitrate of iron.

The following formula shows chemically the component parts of the nitrate of cop- In the accompanyingdrawing I have illustrated one form of apparatus by which my invention may be carried into effect, although it will be understood that any other suitable apparatus may be employed, my invention residing in the process described.

In the drawing F represents a suitable tank, preferably of Wood, having an open top and ,provided at its lower end with a valved discharge, f. At a short distance above the bottom of the tank is a basket or grate, G, hav-v ing vertical side bars, 9, terminating at a point above the top of the tank in eyes, g, to which hoisting chains, h;may be attached to remove the grate from the tank, when necessary. The grate, G, and bars, g, are preferably constructed of gun metal, or metal which will not be acted upon by the acid. Above the tank is a valved pipe, I, through which water issupplied in the flushing operation hereinafter described.

At a point below the tank, F, is a supply tank, K, having an upper open end, while preferably at various levels on one or more sides are taps, Z, through which the contents treated having a greater affinity for the acid radical of the said salt of copper than the metal contained in the salt of copper, it is attacked by the acid radical and the metal previously contained in solution, having less affinity for the acid radical, is immediately precipitated to the bottom of the tank. After a time the coating is entirely removed and held in solution, whereupon the metal com prising the base of the metal operated upon,

having a greater afliinity for the acid radical, is attacked by the acid and the metal previously held in solution is precipitated in the metallic form. WVhen all the metal previousl y forming the coating metal has been precipitated the liquor and the precipitated metals are drawn off from the tank, F, through the trough or pipe, M, to the tank, K. By subsequently flooding the tank, F, with water all the remaining particles of metal are washed to the bottom of the tank, F, when the water and remaining precipitate are drawn oi, as before, to the tank, K. The grate, G, which may, if desired, be provided with sides to form a cage, or basket, is then removed by the hoisting ropes or chains, h, and the metal forming the base removed. The precipitated metal contained in the tank, K, is removed therefrom after the liquor has been drawn off from said tank. In the drawing I have shown steam sup plypipes, s, surrounding the cage, or basket, in which the tin is contained, so that, if necessary, heat may be used to facilitate the operation, said pipes being composed of any metal which the solution will notattack.

Having thus described my invention, what I claim, and desire to secure by Letters Patout, is-- 1. The process of separating a coating metal from the coated article, the coating metal of which is more electro-positive than the base of. the soluble compound employed in the process and the metallic basemetal is more electro positive than its coating, said process consisting in subjecting the coating metal to the action of a neutral salt of copper of the nitroxyl group, precipitating the metal originally held in solution, the coating metal taking its place in the solution, substantially as herein described.

2. The process herein described of removing metal coating from a metallic base wherein the metal coating to be treated is more electro positive than the base of the soluble compound employed and the metallic base metal is more electro-positive than its coating, said process consisting in immersing the coated metal in a neutral soluble salt of copper of the nitroxyl group, thereby producing a precipitation of the metal of the salt of copper in which the combined metals to be treated are immersed by the greater affinity of the coating metal for the acid radical of the said salt of copper, and dissolving the coating metal and holding the same in solution, subsequently precipitating the said coating metal by the greater affinity of the base metal for the acid radical.

3. The herein described process of removing metal coating from its base wherein the I metal coating to be treated is more electropositive than the base of the soluble compound to be employed and the metallic base is more electro'positive than its coating, said process consisting in subjecting the coating to the action of a neutral solution of nitrate of copper and permitting such action to continue until the copper and coating metal have been precipitated in metallic form.

4:. The herein described process of treating tin scrap consisting in subjecting the tin to the action of a neutral solution of a salt of copper of the nitroxyl group and permitting such action to continue until the copper and tin have been precipitated in metallic form.

5. The herein described process of treating tin scrap consisting in subjecting the tin to the action of a neutral solution of nitrate of copper and permitting such action to continue until the copper and tin have been precipitated in metallic form.

6. The process of treating tin scrap said process consisting in subjecting the tin scrap to the action of a neutral solution of nitrate of copper, permitting such action to continue until the copper and tin have been precipitated and nitrate of iron formed, then removing the precipitate with the nitrate of iron, flushing the remaining iron and finally removing said iron.

In witness whereof I have hereunto set my hand this 29th day of January, A. D. 1894:.

THOMAS G. HUNTER.

Witnesses:

JNo. E. PARKER, HORACE PETTIT. 

